A development in the field of gas turbine engines is the use of brush seals to provide a sealing mechanism between adjacent cavities. Brush seals include one or more rows of bristles sandwiched between a backing plate extending nearly the length of the bristles and a shorter front plate. The densely packed bristles engage a rotating surface to discourage fluid flow between the brush seal and the engaged surface.
Brush seals provide an advantage over other conventional seals, such as knife edge seals in many applications. The brush seals are relatively inexpensive, lightweight and provide continued sealing as they wear. In addition, if excessive wear occurs, the brush seals are relatively inexpensive to replace.
In typical applications, the sandwiched brush seals are loosely mounted between a stationary surface and a sheet metal clamp. During operation, high pressure fluid within one cavity presses the bristles against the backing plates and the forces generated by the pressure differential are reacted by the support surface. In this way the dense packing of the bristles is maintained. The sheet metal clamp keeps the brush seal in place during non-operational conditions but provides little or no support during operation.
Unfortunately, the need for a support surface may negate the ability to use brush seals in applications where there is no available structure to mount the brush seal against. This situation may occur if the, lower pressure cavity is on the same side as the rotating components. Using the rotating components to provide the support surface is impractical and would rapidly degrade the brush seal.
The above art notwithstanding, scientists and engineers under the direction of Applicants' Assignee are working to develop effective uses of brush seals in gas turbine engines.